By default sub and sub-sub categories will display on member's profiles, once these have been selected by the member in the Additional Details form:

In order to display only the sub-sub categories navigate to Settings - Advanced Settings. Search for the setting with the name: show_subs_member_profile  and turn this setting On 

Once the setting is On, member profiles will show up like this

Only Sub-Sub categories will show up in the Specialties tab.